VTOL DOWNWASH IMPINGEMENT STUDY. DUCT ADAPTER TEST PROGRAM
HILLER AIRCRAFT CORP PALO ALTO CA
Pagination or Media Count:
A cold air source of approximately 6 sq ft cross sectional area was provided by a mobile test rig. An adapter was fitted to the air source with two one-foot diam ducts that were tested at ZD ratios from .5 to 3 and at disk loadings between 8 and 150 lbsq ft. The air source, without the use of adapters, provided the geometry for a plenum chamber type G.E.M. and an adapter was ATTACHED TO SIMULATE AN ANNULAR NOZZLE TYPE G.E.M. The G.E.M. configurations were tested at a height above the surface of .25 ft effective ZD of approximately .1 and at base loadings in the range of 2 to 30 lbsq ft. Tests were run over a non-eroding surface, plowed lean clay, river bed gravel, dry sand and a fresh water pond. Mutual interference of the side by side ducts is restricted to a narrow band in the region of the equipotential plane where greater air mass flow and erosion rate result. When operated over eroding surfaces the annular nozzle G.E.M. produces considerable vertical projection of dust and particles while the plenum chamber flow is generally along the surface away from the base area.
- Soil Mechanics
- Military Aircraft Operations